1. Technical Field
This disclosure generally relates to methods for making elastomeric gloves, and more specifically relates to methods for making elastomeric gloves that include one or more coatings derived from oats.
2. Background Art
As is known in the art, flexible impermeable elastomer-based gloves include both disposable gloves and reusable gloves. The aforementioned gloves (as well as certain other flexible elastomeric articles which are used adjacent the skin or other membrane of a user's body are thin, flexible, and fluid impermeable. The substrate body of the glove can generally be formed from any of a wide variety of natural rubbers and/or synthetic elastomeric materials known in the art. For instance, some examples, without limitation, of suitable materials useful in making the glove substrate body include, but are not limited to, certain materials characterized as SEBS (styrene-ethylene-butylene-styrene) block copolymers, SI (styrene-isoprene) block copolymers, SIS (styrene-isoprene-styrene) block copolymers, SBS (styrene-butadiene-styrene) block copolymers, SB (styrene-butadiene) block copolymers, natural rubber latex, nitrile rubbers, isoprene rubbers, chloroprene rubbers, polyvinyl chlorides, silicone rubbers, elastomeric polyurethanes, neoprene, butadiene methylmethacrylates, acrylonitriles, acrylate-based hydrogels, and combinations thereof. Other suitable elastomeric materials can also be used to form the substrate body of the glove. Those skilled in the art are well aware of the various materials from which such gloves can be made.
The glove substrate body is generally considered to be that structure which provides the primary structural strength to the glove. The glove substrate can be fabricated with a single layer of substrate material, or multiple layers of substrate material. In gloves which have multiple substrate layers, all the layers can be defined by a common substrate material composition, or one or more of the layers can be defined by second and optionally additional different substrate material compositions.
In fabricating a glove, typically, the elastomer composition from which gloves are to be formed is expressed in a liquid form. For example, the elastomer can be suspended in an emulsion. Glove molds, for example ceramic molds, are dipped into the emulsion, thereby coating material from the emulsion onto the molds. The molds can be removed from the emulsion, the liquid carrier can be flashed off from the molds, and the latex can be cured and/or vulcanized or otherwise treated, thereby to leave the glove substrate material coated onto the respective molds. The glove substrates can be coated with a donning agent, then stripped from the molds and inverted. The glove substrates are typically inverted in the process of being stripped from the molds. In the alternative, the glove substrates can be first stripped from the mold without having been coated with a donning agent, and subsequently coated with any desired donning agent.
A typical glove has a non-wearer-contacting surface, generally referred to as an “outer surface”, or an “outside surface”. The glove also has an opposite, wearer-contacting surface.
The materials commonly used to form glove substrates and substrate layers, for example natural latex rubber, tend to be sticky or tacky, which makes it difficult to don the glove, namely to put the glove on the user's hand. The commonly-used substrate materials also tend to trap perspiration from the user's hand inside the glove.
Disposable gloves are widely used by members of the medical community, the scientific community, and the industrial community to protect the wearer from chemical exposure, mechanical abrasion, environmental hazards, and biohazard contamination, and to prevent transmission of disease or contaminants. Health care providers commonly wear gloves for a single use while performing surgery or other medical or dental procedures such as patient examinations. Thus, the gloves which are the subject of this disclosure are often referred to as disposable examination gloves or disposable surgical gloves, and in general as disposable gloves.
The glove substrates of gloves discussed herein are designed to be generally impermeable to biological fluids, tissues, and solids which are produced by the body, as well as being generally impermeable to other contaminants (human or animal), thus advantageously protecting the wearer from fomitic transmission (transmission by objects that harbor pathogenic organisms) of pathogens and diseases.
Gloves are also worn by individuals who wish to protect their hands from various chemicals, materials, and objects which may irritate, damage, dry out, or otherwise negatively affect the user's skin, and which may be harmful or potentially harmful if allowed to contact or permeate the dermal barrier. Scientists, cleaning service workers, food processing workers, food handlers, law enforcement workers, beauticians or other workers having special protection needs, wear such gloves in the occupational environment. Thus, gloves discussed herein can also include protective gloves or industrial gloves. Also, some gloves, for example household gloves or gardening gloves, are made with more durable substrates, for example thicker substrates, whereby the gloves are considered reusable gloves because they can be used multiple times prior to disposal, and the anticipated uses carry lower risk of deleteriously contaminating the user from outside sources, or of deleteriously contaminating a person being serviced by the user.
In a medical or other intimate use environment, flexible elastomer articles, such as disposable gloves, are frequently changed by the wearer during the day between patients or between procedures or other activities. Allergy and irritation potential of a finished disposable glove has been exacerbated by common glove manufacturing practices of using vulcanizing accelerators, antioxidants, certain powders and other additives as a means to speed production of the glove substrate, to ease donning of the glove, to prevent or cover tackiness, to enhance durability during storage and use life of the glove, and the like. In addition, when conventional disposable gloves cover the hand, moisture (perspiration) is trapped between the skin of the hand and the inner surface of the glove, contributing to hand dermatitis, and potentially other skin problems. Some healthcare providers assertedly struggle with allergic or irritant contact dermatitis or IgE mediated latex hypersensitivity (Type I) whereby such individuals carry an artificially heightened susceptibility to skin disease or infection.
In attempting to address such skin-care issues, some glove users apply lotions, creams, and/or other emollients in attempts to moisturize their hands. Such emollients frequently are oil-based which can deleteriously affect a natural latex rubber glove. Further, such emollients sometimes contain certain antigenic chemicals which serve to exacerbate the above-mentioned and/or other skin problems.
The art has responded to the tackiness and donning problems of elastomer-substrate gloves in a number of ways. One solution which has been suggested for addressing the aforementioned donning problems is to treat the glove with a powder, such as cornstarch, oat starch, talcum (talc) powder, other starch dusting powders, polyglycolic acid powder, insoluble sodium metaphosphate powder, magnesium carbonate, or granular vinyl chloride polymer. Some such powders are used in combination with other powders or with other ingredients. Most elastomers from which the glove substrate is made are inherently sticky on their surfaces, causing a blocking effect, which makes it difficult to don the glove, put the glove on, without the assistance of a donning agent. Commonly, a cross-linked cornstarch powder is used inside the glove, as a donning agent, to facilitate donning the glove.
The aforementioned powders can provide apparent comfort to the wearer's hand as the hand moisture builds up within the glove as the glove is used, but conversely can also act to dry, to abrade and/or to otherwise irritate the user's skin.
The substrate materials most commonly used in fabricating glove substrates which are used to make gloves are natural latex rubbers. It is known that natural latex rubber antigenic proteins migrate to the surface of a disposable natural latex rubber glove substrate, or other flexible article, and are known to have a propensity to electrochemically bind to the cross-linked cornstarch powder particles which are typically used as a donning coating on such natural latex rubber gloves.
The cornstarch particles serve as vehicles to carry the antigen proteins. Such carrying of the proteins has been shown to be problematic to a fraction of the users of such gloves, in that a certain amount of the powder may be aerosolized from the glove during normal use and disposal of the glove. Such aerosolized powder particles can be inhaled by the wearer of the glove, or other person in the vicinity, during normal breathing, whence such powder is delivered to the immunoactive tissue of the nasopharynx and the bronchial tree, where the respective proteins may be harmful. This delivery and corresponding bodily response mechanism occurs because macrophages and specialized T cells and B cells which are concentrated in the tissue of the nasopharynx and bronchial tree become sensitized and produce IgE specific antibodies, which recognize the natural latex rubber antigens, carried by the cornstarch. Thus, cornstarch powder used in natural latex rubber gloves can cause systemic natural latex rubber allergies and skin irritation, and can exacerbate contact allergies.
Another problem with the use of certain powders, such as talc and cornstarch, in surgical gloves is the concern about adhesion formation in a patient's surgical site. This is a particularly significant problem as an intraperitoneal postoperative complication where adhesions of the bowel cause significant sequellae in some patients. As a partial response to this issue, surgeons are provided with towels after donning surgical gloves, for use to wipe off as much of the powder as possible. However, such procedure is not completely successful whereby a certain amount of powder remains on the gloves after such wiping action. The remaining powder particles are known to be responsible for irritation which allegedly can produce scarring in the surgical site, which scarring can be responsible for development of adhesions. The adhesions are caused by mechanical irritation of the tissue when the powder particles are sequestered in the surgical site.
Such complications in the surgical site have been instrumental in the development of glove coating alternatives for gloves which are used for surgical procedures. Such alternatives replace gloves which are coated with powdered talc or corn starch, with powder free gloves which are coated with a powder-free coating.
Balanced against the disadvantages of using surface powders such as talc, cornstarch, and oat starch, is the advantage that surface powders assist in mitigating the inherent tackiness of most elastomers, as well as in facilitating donning the gloves. In order to detackify the non-wearer-contacting surface of the elastomer glove, a detackifying agent needs to be applied to that surface as well. A detackifying agent can be applied to the non-wearer-contacting surface as part of normal processing of a glove disposed on a glove former, to which powder is applied at the wearer-contacting surface. Such gloves can be stripped from the substrate-forming mold after being coated with powder, and can be subsequently processed in a tumbler in order to more evenly distribute the powder and/or to remove any excess powder. During such tumbling, some of the powder is dislodged from the inner surface of the glove, and contributes to the powdering of the outer surface of the glove. Thus, by the time the glove has passed through the tumbling process, powder is present on both the wearer-contacting surface of the glove and on the wearer non-contacting surface of the glove. Typically, and desirably, there is more powder on the inner surface of the glove than on the outer surface of the glove. The powder on the inner surface of the glove prevents the glove from sticking to itself and aids in the donning of the glove. The powder on the outer surface of the glove prevents adjacent gloves, e.g., in a box of gloves, from sticking to each other. Thus, the surface powders, when acting as detackifiers, reduce the tendency of a glove to stick to itself such as on the inside of the glove, and to stick to other gloves when a plurality of gloves are tightly packed together in glove dispensers, or boxes of gloves. Thus, it is seen that the surface powder coatings act as detackifiers to prevent the surfaces of the gloves from sticking to each other, either within a given glove, or glove-to-glove. In addition, the surface powder coatings act to facilitate donning of the gloves.
Use of a powdered donning lubricant such as talc, cornstarch, or oat starch is preferred by some glove users, over lubricant coatings applied to the wearer-contacting surface of the glove or to powder free gloves, in some respects because powder-based donning lubricants are effective to reduce frictional forces which must be overcome when the glove is put on/donned by the user.
Some fabricators of gloves have used halogenation, such as chlorination, and neutralization to solve the tackiness and donning issues of gloves which employ elastomer-based substrates. Other fabricators of gloves which employ elastomer-based substrates have used other surface treatments such as powder free glove coatings using alternative lubricants, for example silicone treated gloves, polyurethane treated gloves, gloves treated with a polymer coating such as an acrylic coating, to solve the aforementioned problems with tackiness, as well as to address the issues attending powder-coated gloves in surgical uses. Such surface treatments typically include coatings applied to the wearer-contacting surface of the glove.
A coating is a material which provides an additional functionally effective layer, whether continuous or discontinuous, on the surface of the glove. Where the coating is discontinuous, generally the coating is provided by a powder which is resident on the inner surface of the glove as well as being optionally resident on the outer surface of the glove. The quantity of the powder, or rate of addition per unit area of the glove, is typically higher on the inner surface of the glove than on the outer surface of the glove.
Where the coating is continuous, the coating is typically defined as a continuous film which has been deposited on at least one of the inner surface and the outer surface. In a film-type coating, the rate of addition per unit area is typically directly related to the thickness of the coating whereby the relative quantity of coating material on the inner surface and the outer surface can be related to the relative thicknesses of the coatings on the respective surfaces. Similarly, the uniformity of the coating can be determined by measuring the thickness of the coating at various locations on a given surface.
In light of the issues related to skin problems with elastomeric gloves, there exists a demand for gloves which have improved coatings, both powder coatings and non-powder coatings.
There further exists a demand for coatings which use less coating material while achieving the combined objectives of ease of donning the glove and reducing the cost of the coating.
There also exists a demand for coatings which are less costly to produce per unit mass, and which can be employed in less mass per glove.
There still further exists demand for coatings which can be produced in the same geographical regions where high volumes of glove substrates are being produced.
There exists yet additional demand for gloves which provide pleasant tactile feel to the wearer of the glove.
There exists yet further demand for coatings which address and ameliorate skin problems which purportedly can attend use of such gloves.
There exists a yet further demand for coatings which address and ameliorate the skin problems which commonly attend use of such gloves by incorporating in the coatings material which is pharmaceutically effective as a skin protectant in treating the types of skin problems which are commonly developed by people who use such gloves for substantial portions of their work days.